Perhaps you should try some spelling variations:
dang quang » dung quang, nang quan, dang hung
hieu suat » hieu luat, hieu qua
tinh dang » tinh dung, binh dang, tinh sang
van hieu » cao hieu
ban kien » ban dien, ban tieng, phan kien
van kien » van tien, van hien, van chien
luan » quan, lan

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( trinh dung luan van hieu suat ) or ( tinh dang quang ((ban kien) or (van kien)) ha ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( trinh dung luan van hieu suat ) OR ( tinh dang quang ((ban kien) OR (van kien)) ha )).
• Adding a wildcard symbol may retrieve word variants: (( trinh dung luan van hieu suat ) or ( tinh dang quang ((ban kien) or (van kien)) ha ))*.